The 12 ways physically bolt right in where the 6 way seats were. The same goes for swapping a 2nd row bench for factory second row captains chairs. The only thing about the 2nd row swap is that the second row plastic carpeted floor panel cover is unique to a bench. Captains have a 2 piece cover. The carpeting is the same for bench or captains chairs.

Wiring the 12 way seats is more complicated. Harnesses are drastically different and wiring size, color and quantity do not match. I should have a wiring schematic posted this weekend. Heat and memory functions are not easy to do for a vehicle that didn't have the factory harnesses and door switches installed.

Yes it is possible, and not that overly difficult if you are just worrying about the power functions and not heat/memory.

In short, the "power" wire (12V main) is larger gauge redish-pink, possibly with a white stripe (varies on some vehicles). That's the main power for the motors at the driver's seat harness and is present in all GM's with power seats. It's pretty easy to notice as it is 12 or 14 gauge while the rest of the wires are 18 guage. In the LS and vehicles without a power passenger seat, there is no 12V power wire to the passenger seat. Your options are to either run a new 12V lead from the battery or use a automotive grade jumper to pull power off of the main wire at the driver's harness. If you jumper the wire at the harness, I do not recommend operating both power seats simultaneously, although the wire is fused. Plan your circuits and mods ahead of time, because if you are adding a center console to replace the center jump seat, you will need a good 12V supply for that as well for the cigar lighter circuit in the console.

The hassle on these comes in when you have to tie-in the wires for seat belts, weight sensors and system logic functions. As I posted elsewhere, the wire colors do not match up. I believe the LS has a 6 wire harness on the driver side and a 4 or 5 wire harness on the passenger side. The 12 way seats have a 30+ wire harness on each side. You also have to run a new ground wire for the passenger seat motors.

If the new 12 ways are being pulled from a donor vehicle, it is best to cut wires on the vehicle side of the harness about 12 inches back, just removing the harness at the connector leaves you with no real option to connect the seat harness to the vehicle. GM uses a unique wire terminal on these wires that you don't find in a store, so it is just as easy to join wires by soldering and heat shrinking new terminals onto both the seat wire and the vehicle wire.

The major problem with the heat and memory functions is that they are controlled by a computer located in the bottom cushion of the driver's seat. That controller is integrated into the vehicle logistics and LAN, so it does not operate on just 12V alone.

Whenever you are messing around with these, you have to be very careful of the small green wires that are everywhere as those are the LAN system. Hack one of those and you will start to have all sorts of things go haywire. I would suspect that many of the problems listed on this board relating to accesory function "happenings" are related to interference in those wires somewhere.

To wire the 12-way seats, the following wires must be connected at a minimum:

(the first wire listed is the wire color from the body side harness and the second wire is the wire color and pin position on the 12 way seat harness)

Driver's side:

Green to Green A6
Brown/White to Brown/White A5
2 small red wires to 3 small red wires A3, A8 and A11
Black to Black B8
Large Red/White to Large Red/White A7

Passenger Side:
New 12V Power (Red) to Red/White B9
New Ground (Black) to Black A9
green to green A10
orange to orange A5
black/white to black/white B3
small red to small reds in both B5 and B6 position
red/white to red/white B2

The power and ground (B9 and A9) wires for the passenger seat have to be added by the installer. The power wire for B9 can be split off from the A7 power wire on the driver's seat side, but doing so may draw too much current for simultaneous use. Running a separate 12 V lead fused at the battery is another option. The ground wire A9 on the passenger side can be run to any ground point, body bolt or even the seat base mount, but be sure you have metal-to-metal contact.

The other mess of wires in each harness are for the door mounted memory position switches and heated seat functions. The memory wires in the harness also control memory positions for adjustable front pedals. In purchasing a 12-way seat, you are getting the brains for the memory and heat functions, so all you are missing is the switches with logic circuit function.

Also, please note that the wire sheating color varies slightly from vehicle to vehicle, meaning the pigmentation of the color may be off a bit, complicating matters when you get to red and pink, dark and light green, etc.

Wow! I picked up some seats a year ago and haven't found any info to get them connected. Thanks for the info Diesel. You said that the brains are in the seats and all that is needed are the switches. Would if be feasible to run the required wiring from the doors to the seats? I will be very happy with just the power features, but more is always better if it's not too difficult. Thanks for the info.

Is it possible, yes. The amount of work on this depends on what you already have. I would not attempt the heat and memory function on this without the factory switches on the door handles. Depending on the quality of the new door panel, you may or may not have a good run of wire to get you back through the base of the A pillar. I am also not sure of the impacts of not having the adjustable pedals on the logic circuit.

I cannot stress enough how unforgiving these vehicles are with the LAN circuits. Get the wrong thing connected up and you're really looking for trouble.

I'll get around to decoding the rest of the wiring on the 12-way harness and post them as well. All of the information comes from the factory wiring diagrams. Unfortunately though, the diagrams do not show the plugs in question. Each circuit has to be traced based on the diagram for the particular system.

I certainly don't want to go overboard trying to get these seats to work. I wanted to upgrade to leather and thought getting the additional power seat options would be a plus. When the connectors turned out to be completely different, it looked like I wasn't going to have any luck. Your info was the first I found to get them working. Getting the door switches that match the seats would be possible, but I wouldn't have the correct wiring running from the switches to the seats. When it warms up a little, I'll rig together a jumper to see if I can get the power functioning. Thanks for the help. I'll post an update after I give it a try.